Mobula thurstoni

Description:

The Bentfin Devil Ray (Mobula thurstoni) is one of three Mobula rays with a worldwide distribution. Mobula are slow-growing, large-bodied migratory, planktivorous animals with small, highly fragmented populations that are sparsely distributed across the tropical and temperate oceans of the world. Their biological and behavioural characteristics (low reproductive rates, late maturity and aggregating behaviour) make these species particularly vulnerable to over-exploitation in fisheries and extremely slow to recover from depletion. The lack of specific records of Mobula landings at the species level, mainly as a result of the difficulty in distinguishing between the different Mobula in the field makes assessment of the conservation status of individual Mobula species extremely difficult.

The Bentfin Devil Ray has a highly specialized diet of krill. The species is pelagic in shallow waters. Mating and early life are reported to take place in shallow water during the summer and into the fall, while segregation by size and sex is seasonal.

Mobula rays are caught in commercial and artisanal fisheries throughout their global warm water range in the Atlantic, Pacific and Indian Oceans. Directed fisheries primarily utilize harpoons and nets, while significant bycatch occurs in purse seine, gill and trawl net fisheries targeting other species, including on the high seas. A recent surge in demand for mobula ray products (gill plates) in China and reports of increased direct fishing effort in key range states suggests an urgent and escalating threat to these species.

As large species which feed low in the food chain, Mobula can be viewed as indicator species for the overall health of the ecosystem. Studies have suggested that removing large, filter-feeding organisms from marine environments can result in significant, cascading species composition changes.